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How is it I get a shock from an iPod?

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dave.saylor.aircrafters(a
Guest

Posted: Tue Jun 24, 2014 9:51 pm Post subject: How is it I get a shock from an iPod?

Here's a non-aviation question for the group.  Unless you fly with an iPod, I guess.

  Background:

My son complained today that he got shocked by an iPod.  FWIW, it's a 5th gen nano plugged into an Apple USB charging cube by an Apple charging cord--not knock-off parts.  First I said yeah, right...but he insisted so like an idiot I figured I'd show him how that was impossible....and of course I got shocked too.  Not as strong as 120VAC but enough to get my attention.

  



We were both barefoot (key, I think...) on a concrete slab, in the garage.  It happened when either of us touched the metal lock switch.  I've never had any issues with the power strip we were using.

  



Putting a meter between the lock switch and ground I measure an invigorating 60VAC.  Between the neutral of the power strip to any other ground is zero, so I figure the power strip is wired correctly. Inverting the cube (it's not polarized) makes no difference, still 60VAC.

  



I tried a few things: different plug, no shock.  Different cord, no shock.  Different cube, no shock.  I went back to the original combination:  BZZZZT.  So it is repeatable.

  



There's an Apple support document describing the possibility of static shock when using their device.  This was not your typical feet-on-carpet-touch-a-doorknob static shock. It was sustained as long as I touched the lock switch.

  



The iPod works and charges just fine except for that particular combination of parts.

  



Questions:

In general, how is it that an iPod can give me an electric, non-static shock?  I thought that USB was only 5V. How does more than 5V get into the system?  Or more appropriately, how does it get out of the system?  Could this happen from a 12V system, or is part of the 120V getting through?

  



Thanks for tolerating a non-airplane topic,

  --Dave Saylor

 

  [quote][b]

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etienne.phillips(at)gmail
Guest

Posted: Tue Jun 24, 2014 10:48 pm Post subject: How is it I get a shock from an iPod?

Hi Dave



I think it's an Apple thing - I get zapped by my aluminium Macbook Pro, exactly how you describe it - when it's plugged in. Sometimes it's actually painful, since the skin in the inner arms is pretty sensitive! I don't know if it's any different here in a 220V country, but I'd really like to get to the bottom of it. It's happened at multiple locations, which leads me to believe that it's also not affected by the supply wiring.

 



Thanks

Etienne



On 25 June 2014 07:49, Dave Saylor <dave.saylor.aircrafters(at)gmail.com (dave.saylor.aircrafters(at)gmail.com)> wrote:

 [quote]Here's a non-aviation question for the group.  Unless you fly with an iPod, I guess.

 



  Background:

My son complained today that he got shocked by an iPod.  FWIW, it's a 5th gen nano plugged into an Apple USB charging cube by an Apple charging cord--not knock-off parts.  First I said yeah, right...but he insisted so like an idiot I figured I'd show him how that was impossible....and of course I got shocked too.  Not as strong as 120VAC but enough to get my attention.

   



We were both barefoot (key, I think...) on a concrete slab, in the garage.  It happened when either of us touched the metal lock switch.  I've never had any issues with the power strip we were using.

   



Putting a meter between the lock switch and ground I measure an invigorating 60VAC.  Between the neutral of the power strip to any other ground is zero, so I figure the power strip is wired correctly. Inverting the cube (it's not polarized) makes no difference, still 60VAC.

   



I tried a few things: different plug, no shock.  Different cord, no shock.  Different cube, no shock.  I went back to the original combination:  BZZZZT.  So it is repeatable.

   



There's an Apple support document describing the possibility of static shock when using their device.  This was not your typical feet-on-carpet-touch-a-doorknob static shock. It was sustained as long as I touched the lock switch.

   



The iPod works and charges just fine except for that particular combination of parts.

   



Questions:

In general, how is it that an iPod can give me an electric, non-static shock?  I thought that USB was only 5V. How does more than 5V get into the system?  Or more appropriately, how does it get out of the system?  Could this happen from a 12V system, or is part of the 120V getting through?

   



Thanks for tolerating a non-airplane topic,

   --Dave Saylor

 

   	  Quote: 	
		  



ist" target="_blank">http://www.matronics.com/Navigator?AeroElectric-List

tp://forums.matronics.com

_blank">http://www.matronics.com/contribution



	
[b]

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john.maccallum(at)bigpond
Guest

Posted: Wed Jun 25, 2014 3:19 am Post subject: How is it I get a shock from an iPod?

HI Dave,

I think Carl can probably answer this best but I should think it’s caused by the Switch mode power supply of the Charger and a floating ground coupled with

Double Insulation. In layman’s terms the charger is building up a charge because it’s not earthed and because you are by standing on the ground (or concrete) you get a small amount of 

Current that flows through yourself from Ground. Therefore if your skin resistance is low enough you feel a slight tingle. This often happens with other devices that have floating grounds.

Tv’s, Stereo Systems and other such devices.

It’s gets to be more than 5 volts because the power supply has internal high frequency switching transistors that are driving an output  transformer the primary winding of which is at least at 

110 volts, (in the US and 240 volts here in Australia).

I don’t think it is really correct for Apple to refer to it as a static charge because usually if you continue to touch the device the tingle will persist because the source of the current is still present 

but others may have more information on that subject.

 

Cheers

 

John MacCalllum

 

 

From: owner-aeroelectric-list-server(at)matronics.com [mailto:owner-aeroelectric-list-server(at)matronics.com] On Behalf Of Dave Saylor

Sent: Wednesday, 25 June 2014 3:49 PM

To: aeroelectric-list(at)matronics.com

Subject: How is it I get a shock from an iPod?



 

Here's a non-aviation question for the group.  Unless you fly with an iPod, I guess.



 



Background:



 



My son complained today that he got shocked by an iPod.  FWIW, it's a 5th gen nano plugged into an Apple USB charging cube by an Apple charging cord--not knock-off parts.  First I said yeah, right...but he insisted so like an idiot I figured I'd show him how that was impossible....and of course I got shocked too.  Not as strong as 120VAC but enough to get my attention.



 



We were both barefoot (key, I think...) on a concrete slab, in the garage.  It happened when either of us touched the metal lock switch.  I've never had any issues with the power strip we were using.



 



Putting a meter between the lock switch and ground I measure an invigorating 60VAC.  Between the neutral of the power strip to any other ground is zero, so I figure the power strip is wired correctly. Inverting the cube (it's not polarized) makes no difference, still 60VAC.



 



I tried a few things: different plug, no shock.  Different cord, no shock.  Different cube, no shock.  I went back to the original combination:  BZZZZT.  So it is repeatable.



 



There's an Apple support document describing the possibility of static shock when using their device.  This was not your typical feet-on-carpet-touch-a-doorknob static shock. It was sustained as long as I touched the lock switch.



 



The iPod works and charges just fine except for that particular combination of parts.



 



Questions:



 



In general, how is it that an iPod can give me an electric, non-static shock?  I thought that USB was only 5V. How does more than 5V get into the system?  Or more appropriately, how does it get out of the system?  Could this happen from a 12V system, or is part of the 120V getting through?



 



Thanks for tolerating a non-airplane topic,



 



--Dave Saylor



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 [quote][b]

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racerjerry

Joined: 15 Dec 2009
Posts: 202
Location: Deer Park, NY

Posted: Wed Jun 25, 2014 3:20 am Post subject: Re: How is it I get a shock from an iPod?

Buy one of those cheap LED type plug-in polarity testers from a home improvement store and check the polarity of your garage outlets.  It sounds like you may have a dangerous condition in your shop with possible wire polarity reversal and/or a grounded neutral.  For about 5 bucks, the tester will quickly alert you of any problem.  



Another good idea is to retrofit a ground fault circuit interrupter (GFCI) into garage outlets – now required by code for new construction.  A single GFCI will protect all downstream outlets, so a GFCI is not required at every outlet for protection and retrofitting is not a big deal.  GFCI’s are LIFESAVERS.



Your shock may be a wake-up call to a larger and quite dangerous problem – for the sake of your children and their breadwinner, please don’t ignore it.

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_________________
Jerry King

Eric M. Jones

Joined: 10 Jan 2006
Posts: 565
Location: Massachusetts

Posted: Wed Jun 25, 2014 5:43 am Post subject: Re: How is it I get a shock from an iPod?

 	  Quote: 	
		  Putting a meter between the lock switch and ground I measure an invigorating 60VAC.  Between the neutral of the power strip to any other ground is zero, so I figure the power strip is wired correctly. Inverting the cube (it's not polarized) makes no difference, still 60VAC. 	




The actual ground to neutral is never zero, but it should be less than 3VAC. But this is probably not the problem. Sounds like you have a bad charger, Dave. And don't think because this is a common problem that it is acceptable. They could all be bad.



do not archive

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_________________
Eric M. Jones
www.PerihelionDesign.com
113 Brentwood Drive
Southbridge, MA 01550
(508) 764-2072
emjones(at)charter.net

edpav8r(at)yahoo.com
Guest

Posted: Wed Jun 25, 2014 9:44 am Post subject: How is it I get a shock from an iPod?

Dave,

I think it's likely that the charging cube you have, though it may look like genuine Apple, is actually a knockoff.  There have been many examples of these coming from China, and they almost never have the same safety-minded design as the genuine article.  They look virtually identical, but the insides are a joke by comparison.  If it is an Apple, it clearly has a manufacturing defect.

Obviously, these things convert 120VAC to 5VDC.  Believe it or not, the process involves AC voltages much higher than line voltage.  If the device doesn't have proper allowances in its design for creepage and clearance (distance between high and low voltage sections), it can be a death trap.  I *STRONGLY* recommend that you throw the offending charger away *IMMEDIATELY* and get a new one.  I would stick with either a genuine Apple part, or one of the well-known aftermarket brands like Belkin.

You should never feel an AC shock from any consumer electronics device.  Ever.

Eric

P.S.  Crack the cube open and take a couple pictures of the insides before you toss it.  It's pretty easy to tell the difference between Apple and knockoff.



On Jun 25, 2014, at 12:49 AM, Dave Saylor <dave.saylor.aircrafters(at)gmail.com (dave.saylor.aircrafters(at)gmail.com)> wrote:



[quote]Here's a non-aviation question for the group.  Unless you fly with an iPod, I guess.

  Background:

My son complained today that he got shocked by an iPod.  FWIW, it's a 5th gen nano plugged into an Apple USB charging cube by an Apple charging cord--not knock-off parts.  First I said yeah, right...but he insisted so like an idiot I figured I'd show him how that was impossible....and of course I got shocked too.  Not as strong as 120VAC but enough to get my attention.

  



We were both barefoot (key, I think...) on a concrete slab, in the garage.  It happened when either of us touched the metal lock switch.  I've never had any issues with the power strip we were using.

  



Putting a meter between the lock switch and ground I measure an invigorating 60VAC.  Between the neutral of the power strip to any other ground is zero, so I figure the power strip is wired correctly. Inverting the cube (it's not polarized) makes no difference, still 60VAC.

  



I tried a few things: different plug, no shock.  Different cord, no shock.  Different cube, no shock.  I went back to the original combination:  BZZZZT.  So it is repeatable.

  



There's an Apple support document describing the possibility of static shock when using their device.  This was not your typical feet-on-carpet-touch-a-doorknob static shock. It was sustained as long as I touched the lock switch.

  



The iPod works and charges just fine except for that particular combination of parts.

  



Questions:

In general, how is it that an iPod can give me an electric, non-static shock?  I thought that USB was only 5V. How does more than 5V get into the system?  Or more appropriately, how does it get out of the system?  Could this happen from a 12V system, or is part of the 120V getting through?

  



Thanks for tolerating a non-airplane topic,

  --Dave Saylor

[b]

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